


Baby, It's Cold Outside

by Little_Comett



Category: Undertale (Video Game)
Genre: Bara Sans (Undertale), Christmas Fluff, Christmas Smut, Domestic Fluff, Drinking, Ecto-Genitalia (Undertale), Ecto-Penis (Undertale), Ecto-Tongue (Undertale), F/M, Fluff and Smut, Friends to Lovers, One-Shot, Papyrus is mentioned - Freeform, Shameless Smut, Smoking, Smol Reader, Smut one-shot, Song: Baby It's Cold Outside, Undertale Monsters on the Surface, sans smokes
Language: English
Status: Completed
Published: 2018-12-10
Updated: 2018-12-10
Packaged: 2019-09-15 13:07:17
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,796
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16933779
Author URL: https://archiveofourown.org/users/Little_Comett/pseuds/Little_Comett
Summary: Based off the song: Baby, It's Cold OutsideAfter a long day of decorating the Christmas tree with Sans and Papyrus, you and Sans find yourselves alone at his house with the nagging in your mind of knowing you have to go back home at some point.  Still, Sans isn't willing to let you walk out in the freezing cold just yet.





	Baby, It's Cold Outside

**Author's Note:**

> Literally, I know I've been gone for like, ever, but I'm finally back and I'm gonna be starting a new story and doing some occasional one-shots, both fluffy and smutty. To commence my return, I give you this very lovely Sans smut that I hope everyone enjoys. And no, I will sadly not be returning to either of my other stories. I'll be most likely rewriting them, or simply starting fresh and deleting those. I also might do a Christmas smut/fluff one-shot series. *lazy shrug* Anyway, enjoy!

I breathed out a soft puff of air, standing outside beside my best friend after a long day of decorating his and his brother's house for the upcoming holiday. He took another puff of his cigarrette, smoke slithering out from his nose, mouth, and eye sockets. White pinprick eyelights glanced in my direction as I let out a soft shudder. A smirk immediately tugged at his mouth and I could sense the sarcastic remark before it even came.

"you're cold."

I almost snorted. My eyes snapped up in his direction, brow raising in what I hoped would be an almost sarcastic expression. I could feel my body trembling from the cold.

"Of course I am, Sans. It's probably in the negatives, and you just HAD to come out for a cigarrette," I stated, tugging at my scarf.

Sans snickered to himself, blowing out another puff of smoke. He shrugged off his coat, handing it to me by the fluffy white hood of it.

"i never said you had to come out with me."

I simply stared at the very familiar jacket.

"Yeah, well I gotta go home, Sans. My brother will be worrying."

I saw the skeleton's face fall. His eyes dimmed slightly. He didn't put the coat down, still holding it out for me to grab. Sans knew me better than anyone else, and I the same for him. We both knew exactly what he'd say next.

"or 'ya could keep me company a little longer."

I didn't respond, staring at the coat intently, as if that would change the situation at hand. I knew I really ought to go home. My brother really would worry if I didn't come back without a word to him about what I was doing or where I was. Though, I figured he'd assume I was at Sans' place. I often found myself here.

"come on, ____," Sans pleaded, a smirk tugging at his mouth, "pap is gonna be gone to undyne's all night, probably decorating her christmas tree. it'll be quiet and lonely."

Guilt tripping me, really Sans? Though, it was not surprising. It _was_ Sans. Besides, what's the harm in staying just a little while longer?

I let out a huff, snatching the coat from his hand, tugging it over my shoulders and tightening it around myself. The coat was practically a dress on me, as it always was whenever I'd manage to steal the giant monster's coat. Which was... quite often, frankly.

"'sides, kid, it's freezing out here and you only wore a sweatshirt. you definitely need me around to keep you warm," the monster shot me a wink.

I let out a puff of air, a soft cloud appearing where I let out the breath. I felt my cheeks warm, and quickly tried to hide the blush in the white fur of his coat. Sans chuckled, dropping the cigarrette into the snow, stomping on it to put it out. He hooked a finger on the hood, tugging me toward the door.

"see, kid? i'm good at keeping you warm."

Damn, he saw it.

I stumbled into the house behind him, pouting. I crossed my arms stubbornly.

"One more glass of wine, got it, Sans?" I stated as the skeleton dragged me toward the coffee table, which had three empty glasses of wine and a half-full bottle of our favorite kind of wine.

"pfft, sure."

I plopped onto the couch, pushing aside Papyrus' empty glass, which he'd abandoned for Sans and I to clean up (by Sans and I, what I really mean is just I). Sans sat beside me, his leg brushing mine gently as he leaned forward to grab the bottle. He poured us both another full glass.

I brought the cup to my lips, sipping the drink slowly. Sans ran his finger over the top of his glass. The two of us sat in silence for a while. I let my gaze wander toward the skeleton brothers' Christmas tree, which was the sole purpose of me being here tonight. It was their first Christmas on the surface, and they wanted my help showing them what to decorate. In the end, it was virtually the same as a tradition they celebrated in the Underground.

Sans chuckled beside me, and I drifted my gaze toward him instead.

"What?" I questioned, raising a brow, thinking he had something evil planned.

"nothin'," he was staring at my face... maybe my lips? "ya just look so beautiful."

My cheeks heated up. I stared up at his face in shock, lips parted slightly. I had no idea how to respond. Sans and I were constantly flirting, at least I liked to think that's what it was, but it was always more subtle. He'd never outright admitted to something like that, especially not without a single pun in the sentence.

Sans grinned, his eyes glowing. Suddenly, I found myself wanting nothing more than to kiss him, despite everything screaming at me to go home and freeze this stupid blush off my cheeks.

A cold hand cupped my cheek, and suddenly Sans was pressed against me... or had he pulled me to him that quickly? His teeth pressed against my lips gently. I brought my hands to the ugly sweatshirt that Papyrus had most likely forced him to wear. I bunched the fabric in my fists, kissing back with every bit of affection I had in myself, which for Sans, was a lot.

Sans' other arm slithered behind my back, pulling me closer to his chest. I felt his teeth tug at my bottom lip gently, his blue tongue sliding out and licking at it softly. My cheeks redded. I didn't want to pull away, but I was running out of breath. I pulled away, panting softly, my lips still brushing against his teeth softly.

Sans only chuckled, moving to kiss my jaw softly, his skeleton kisses forcing a sigh from my lips. I tilted my head softly, giving him more room, his tongue dragging across my skin gently.

"I really should get home..." I murmured, knowing that if I let this go much further it really would be late before I got home.

"oh come on, sweetheart... don't leave me _bonely_..." Sans mumbled against my skin, "'sides, you'll freeze outside."

I smiled a bit at the pun, even despite the situation we were in.

"Honestly, Sans... I said only one more drink..." I murmured.

Despite my arguing, there was no way I was leaving this house, despite how much my mind was screaming at me to go home.

"baby..." Sans growled, pressing his teeth into my neck softly, forcing a soft moan from my lips, "come on, don't hurt my damn pride. this is as close as i've ever gotten with you..."

I dragged my lip between my teeth softly, not speaking up. I put the glass of wine on the table, which I'd somehow managed not to spill. Sans pushed me down onto the couch by my shoulders, crawling over me and pressing his teeth onto my lips once more, this time our kiss much more frantic and wanting. I slithered my arms around his neck gently, pulling him close to me.

"Are you sure Papyrus won't be home soon?" I murmured against him.

Sans chuckled, hands sliding beneath his large coat which I was still wrapped in. They slithered beneath my shirt, his eyes twinkling as they moved closer to my chest.

"positive."

Sans pressed his teeth to my neck, fangs gently scraping against the skin. His tongue quickly trailed after the soft scratches, leaving a trail of saliva behind. I moaned softly, every action he took shooting straight between my legs. He squeezed my bra-clad chest, forcing another quiet moan of his name out of me.

"Sans, please..." I begged softly.

I could feel his smirk against my skin. He leaned back, unzipping his jacket from me, tugging it off and tossing it somewhere off the couch. He threw my shirt in the same direction, before fiddling with the clasp of my bra.

I watched in amusement as he struggled with unclasping it. He mumbled a few colorful curses before he finally got it undone, throwing it aside somewhere in annoyance.

"Totally killed the mood there, Sans..." I taunted.

"shut up."

Really, he hadn't. But despite everything, I loved giving the large skeleton shit anytime he did something even remotely humiliating.

Sans' pinprick pupils stared down at my chest, while his hands quickly moved to fondle the flesh. I arched my back into his touch, breathing out a quiet moan of his name. He smirked, watching my reaction, probably evaluating every move I made, as he often did. He leaned down, dragging his tongue between the valley of my breasts, staring at me as he did so.

I suddenly couldn't believe this was happening. Why'd I ever think it was a good idea to go home?

Sans slid on hand down the front of my pants, running a finger along my folds through my underwear. He groaned a bit, staring at me.

"fuck, you're wet..." He growled.

I swallowed my embarrassement from the lewd comment, instead focusing on my hands as they slid beneath his t-shirt. I gently hooked my fingers on his ribs, which forced another groan from him. He pressed his forehead into my shoulder, sliding his hand beneath the last of the fabric seperating us. I moaned as he rubbed my clit, finger taunting my entrance.

"Sans, please..." I moaned, "please t-touch me..."

Sans smirked. He pressed the tip of his middle finger against my entrance.

"please, what?" He murmured, voice low and taunting, "please... touch you? please... fuck you into the couch? or, if i recall correctly, didn't you need to walk home to your brother?"

I groaned at not only his stupidity, but also mine.

"Touch me."

Sans slid one finger into me, his sternum pressed into my chest. His eyes focused on the hand stuffed down my pants. I moaned, grip tightening on his ribcage, forcing a strangled groan from him. He moved his hand, adding another finger as he went.

"you're fucking hot..." He growled lowly, "fucking hell, kid..."

I whimpered, throwing my head back against the arm of the couch.

"S-Sans, please... Please, more..." I begged through moans.

Sans abruptly pulled his hand out of my pants. He lewdly dragged his tongue across the liquid on his fingers, before moving to tug off my pants and underwear, leaving me completely naked. I all but tore off his t-shirt, wanting to see the bones underneath. I ran my fingers down his sternum gently, tracing over the smooth bone.

Sans groaned, lowering his head and pressing his face into my chest. I trailed my fingers over every rib, coming close to gently touching the white heart in his ribcage.

"No wonder you wear so many layers... Your ribs are sensitive~" I hummed teasingly.

"so's your neck," he retorted without a moment's hesitation, biting down into the flesh of what made up his comeback.

Sans slid away from me, sitting back on his feet. He grabbed my ankles, spreading my legs open wide for him. I flushed immediately at being so exposed. He smirked, hand moving back between my legs, immediately shoving two fingers inside me. I arched my back in surprised, letting out a strangled moan.

"Fuck, Sans!"

He leaned down, pressing his tongue flat against the mound of flesh. He stared at me, the pupil in his right eye gone as his left eye glowed with blue flames. He pressed his tongue into my clit, swirling it, building up the pleasure. His fingers moved in and out of me, picking up in pace with his tongue.

"i fucking love it when you say my name..." He growled.

I wrapped my arms tightly around his neck, back arching higher and higher as he built up my pleasure. The knot in my stomach was becoming tighter and tighter.

"Nnnnf... Sans, please... S-Sans..." I moaned loudly, suddenly grateful Papyrus was going to be gone all night.

Sans pressed his tongue into my entrance, joining it with his two fingers. He watched my reaction to every move he made. I dug my fingers into his clavicle, the knot in my stomach finally releasing. I screamed his name, tears forming in my eyes as I came harder than I ever had before. By the time he'd pulled away, I was an exhausted mess beneath him, slowly calming down from the orgasm.

Sans dragged his cyan tongue over his teeth, smirking in triumph.

"you warm enough yet? because i definitely know you're _hot_ enough." He chuckled at his joke.

I rolled my eyes at the joke, a tired smile forming on my face.

"I think I still might be a little too cold..." I teased, pressing my lips gently into the bones of his neck.

His face flushed blue, sweat beading on his skull. He tugged down the front of his shorts impatiently.

"Fuck, Sans... Oh fuck..." I moaned at seeing his size, almost becoming hesitant.

He only smirked, his hands taking hold of the flesh of my thighs, squeezing them as he spread my legs wide enough for him to slid his pelvis between them. I wrapped my arms around his neck, chest pressing into his sternum.

I moaned softly as he slowly started pushing his hips forward. He slid in easily, both of us watching with quiet moans as he sheathed himself fully inside me. I flushed instantly, seeing the soft blue glow of him beneath the skin of my lower stomach in the dark room. He pressed his thumb into my clit, slowly pulling his hips back, before pushing back inside me.

I moaned loudly, no longer caring if anyone could hear me. I was half certain the whole city could hear us. I clung onto him as he picked up speed, my arms wrapped tightly around his neck. His hands gripped my ass, squeezing the flesh as he pulled me closer into him. His pelvis slammed into mine, the hardness of his bones surely going to leave bruises tomorrow but neither of us could give a single care in the world.

"you're so fucking tight..." He moaned, staring at where we were joined.

I moaned loudly, letting out occasional whimpers between every moan.

"Harder, Sans!" I begged, "please, harder, Sans!"

He panted, immediately picking up into a bruising pace. He buried his face against my shoulder, his teeth digging into the flesh, but not enough to draw blood.

"say my name again..." He growled.

"Sans!" I screamed as he dragged me closer to my release.

The skeleton's grip tightened. We were both close. I screamed out as he brought me to my climax, clutching onto him as I rode out my high. He growled out a moan, coming immediately after me, his thrusts frantic and slow as he released inside me. He finally came to a stop as the two of us panted frantically.

A smirk slowly formed on his tired face. Sweat dripped from his skull and onto my chest as he stared down at me.

"can't believe i just fucked you into my couch," was the first thing he said, "my brother'll kill me if he finds out."

I let out a tired laugh, which was followed by a soft hiss as he pulled out and tugged his shorts up, his magic fading. He collasped onto me, his head on my chest and his ribs pressing into my stomach. We laid there silently. I gently traced my fingers over his skull, coming to the realization that he was listening to my heartbeat.

"i love you..."

Those words too me by surprise. I looked down at him, his pinprick pupils already focused on my face. He didn't let me answer before he continued.

"this is 'prolly the worst time to blurt that out, huh?" he chuckled tiredly, "but it's true. 'have for a while. i just didn't have the _balls_ to tell you."

"I love you too, Sans..." I smiled.

His skull flushed. He smiled, rolling over and pulling me onto his chest instead of continuing to lay on me. We laid like that for a while in comfort, before I finally had to speak up.

"Sans, I really should get home now... My brother is gonna kill me..."

Sans was silent for a while, his face buried against my neck. For a minute I thought he had fallen asleep, which would have made it easier for me to sneak away. Finally, I felt his hands move to my rear, tugging me against him tighter, which forced a squeak from my lips.

"but baby... it's cold outside..." he whined, before flipping us over once more, and continuing to 'warm' me up.

 


End file.
